Particle acceleration in axisymmetric pulsar current sheets

By B. Cerutti, A. Philippov, K. Parfrey, A. Spitkovsky. 2014

143 citations recorded by the source corpus.

The equatorial current sheet in pulsar magnetospheres is often regarded as an ideal site for particle acceleration via relativistic reconnection. Using 2D spherical particle-in-cell simulations, we investigate particle acceleration in the axisymmetric pulsar magnetosphere as a function of the injected plasma multiplicity and magnetization. We observe a clear transition from a highly charge-separated magnetosphere for low plasma injection with little current and spin-down power, to a nearly force-free solution for high plasma multiplicity characterized by a prominent equatorial current sheet and high spin-down power. We find significant magnetic dissipation in the current sheet, up to 30% within 5 light-cylinder radii in the high-multiplicity regime. The simulations unambiguously demonstrate that the dissipated Poynting flux is efficiently channeled to the particles in the sheet, close to the Y-point within about 1-2 light cylinder radii from the star. The mean particle energy in the sheet is given by the upstream plasma magnetization at the light cylinder. The study of particle orbits shows that all energetic particles originate from the boundary layer between the open and the closed field lines. Energetic positrons always stream outward, while high-energy electrons precipitate back towards the star through the sheet and along the separatrices, which may result in auroral-like emission. Our results suggest that the current sheet and the separatrices may be the main source of high-energy radiation in young pulsars.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2fef79e8049adcf99b5d64b60b0024d1b510048f

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Citations in the corpus

Modelling high-energy pulsar light curves from first principles (2015, methodology): “Indeed, as mentioned earlier and as shown in Cerutti et al. (2015), reconnection in the current sheet induces an electric field such that E · B , 0, which pushes positrons outward and precipitates electrons towards the star through the Ypoint and the separatrix current layers (see Figure 5).”
Ab-initio Pulsar Magnetosphere: Particle Acceleration in Oblique Rotators and High-energy Emission Modeling (2017, background): “This results in a significant excess of outflowing positrons at highest energies (Cerutti et al. 2015).”
Plasmoids in relativistic reconnection, from birth to adulthood: first they grow, then they go (2016, background): “…close to the boundaries, where a large magnetic island is formed; or (ii ) absorbing boundary conditions in thex direction of the reconnection outflow, to mimic an open boundary in which no information is able to propagate back inward (Daughton et al. 2006; Cerutti et al. 2015; Belyaev 2015).”
Non-thermal particle acceleration in collisionless relativistic electron-proton reconnection (2016, background): “…2011; Uzdensky et al. 2011; Cerutti et al. 2012a,b, 2013, 2014a,b; Uzdensky & Spitkovsky 2014; Philippov & Spitkovsky 2014; Philippov et al. 2014; Cerutti et al. 2015); gamma-ray bursts (GRBs) (Drenkhahn & Spruit 2002; Giannios & Spruit 2006; McKinney & Uzdensky 2012); magnetospheres of…”